Method of preparing satin white



. No Drawing.

Patented June 21, 1921.

UNITED STATES PATENT oFFIcE.

JOHN F. FREDRIKSSON, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE KALBFLETSCHCORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF PREPARING SATIN WHITE.

Satin white is the reaction product of aluminum sulphate or alum andlime and probably consists of calcium aluminate, a small amount ofcalcium sulphate and what- Applicatlon filed February 5, 1925. SerialNo. 7,154.

vessels or containers in which the mixture for use. as it the prolongedagitation, dilution and many processes generally used are 5 ever limemay be-left over in excess. l he cmployed. I have found that, if basicsulill reaction by which it is formed probably takes place in thefollowing manner:

lts principal use is as a surface coating of paper to produce a glossysurface. As generally prepared the process is somewhat complicated andan exceedingly messy one, and besides the product is more or less uncertain. as I will explain below. Usually the materials employed are limeand sulphate of alumina liquor. The lime is slacked in hot water, alarge steel tank being generally used, and the mixture is automaticallyagitated. The milk of lime in the slacker is run through screens inorder to eliminate coarse particles'such as unburnt lime stone, silicaand gravel, and other coarse matter. From the screens the milk of limeis drawn oil into storage tanks, each being large enough to hold onecharge. tanks the milk of lime goes into a large agitated iron tankwhere a measured quantit of aluminum sulphate solution is introduce Thismixture of lime and sulphate of alumina solution is now agitated forseveral hours, and'the mixture is diluted with water (and in some casesscreened) and .run into big reservoirs. from which reservoirs it ispumped through a filter press which removes excess water and gives thepulp product called satin white. The press cakes are I unloaded from thefilter press into the pugging machines, pugged and barrelled.

I have stated the usual process in a general way so that the advantagesor my improved method could be more easily seen, and its simplicity andbetter resulting prodnot appreciated.

l have further discovered that while it has heretofore been considered.essentialto have prolonged agitation and dilution in order to get theproper reaction with the mixture of lime and basic aluminum sulphate,that time is the equivalent of such. prolonged agitation. and thatv thereaction can take place at ordinary room temperature just as well if aproper time is had in the From these phate of alumina is employed and ifdry hydrated lime is mixed therewith -and just enough water is added tothe mixture of hydrated lime and basic aluminum sulphate to give it apasty consistency and the reaction is allowed to take place cold or atthe ordinary room temperature, two new results are attained. (a) due tothe fact that only enough water is added to the mixture to make it intoapasty consistency. all the lime is not brought into solution but merelya small portion thereof is dissolved in the water. It is essential tothe successful working out of this reaction that a basic sulphate ofaluminum be employed. lhe smallquantity of dissolved lime then reactswiththe aluminum sulphate to form the satin white which is precipitated,leaving the water free to dissolve more lime to successively react withmore basic aluminum sulphate. Due to the fact that the reaction isprolonged and successive and also because of the basic sulphate'used.much smaller sized and more uniformparticles of satin white are attainedthan formerly where a large quantity of water and heat-were used tocause the entire reaction to take place substantially at once. I find inpractice that by carefully following out myprocess a much superior satinwhite is produced than formerly; (b) employing my process, at thecompletion of the reaction, the satin white is in a pasty consistency,thereby obviating the necessity of employing filterswhich were formerlynecessary to filter 0d the excess water so that the satin white could beeconomically shipped.

To produce satin white oil the highest possible gloss or finish andtherefore of the highest value to the paper coated, it is necessary tomake the particles ol-the mixture of as nearly as possible uniform andsmall size, and l findthat by using the mixtures in approximately thecombinations stated, I more nearly approach the desired result. Toaccomplish this it employ hydrate of IOU lime, basic sulphate of aluminaliquor, and

i a small quantity of water to form the hydrated lime in a paste. \Vhenthis is done, however, the amount of water added to the mixture ofslaked lime and basic 'sulvphate of aluminum is correspondinglydecreased by theamount present in the slake-d lime. I havefound-,however, that if the hydrate of lime, sulphate of aluminamixture, and enough water to form a paste are mixed well and barrelleddirectly, the reaction will take place just the same, and further, thata. superior article will result because the high concentration exists atall 1 stages during the rocess, and concentration smaller and moreuniform p rticles.

has a very marke influence on the texture of satin white and. a tenden yto prodrulce me time necessary for the reaction to be complete dependsif the water content remains constant, to a considerable extent upon thephysical properties of the mixture, which properties, as said before,canbe regulated by various means. I

The reason that all reactions where lime enters are slow, is that thesolubility of lime in water is very small, and the lime must be insolution before it reacts. As soon as lime in solution has reacted, itleaves the water free to dissolve more lime, that immediately reacts,and so on until the process is complete.

It is obvious that as a small part of the hydrated lime goes intosolution it will react on the basic sulphate of aluminum to form satinwhite which is precipitated, leaving the water free. to dissolve morelime and so that the reaction will successively take place in smallproportions until the h drated lime has entirel reacted with te basicsulphate of alumina liquor to form ture directlyin the containersinwhich it may be shipped or used, I eliminate an extensive, messy,disagreeable and expensive process, while at the same time I get abetter and more uniform product. Under the old process the product isalways more or less a doubtful one, while under my process there issubstantial uniformity, and by reasolrof the more nearly correct size ofsatin white particles, the best effect of refraction is obtained so thatthe product is'of higher ing hydrate of lime and basic sulphate ofalumina liquor and a relatively small quantity of water, and permittingthe mixture to reactat ordinary room temperature without furtheroperations thereon.'

2. The herein described process of preparing satin white, which consistsin mixing a concentrated solution of basic sul hate of alumina withhydrate of lime an enough water to form a paste only and insuflicient tocompletely dissolve the hydrated lime,

and leaving the mixture to react at room temperature.

3; The herein described method of preparing satin white, which consistsin mixinfia solution of basic sulphate of alumina, ydrate, of lime, anda small quantity of water,

ordinary placing the same in a vessel for storage or shipment atordinary room temperature, and permitting the reaction of theingredients to take place in the said container:

1. The herein described method of preparing satin white, which consistsin mixing a concentrated solution of basic sulphate of alumina withhydrate of lime and enough vater to form a paste only placing the same'without further treatment in a contamer for shipment or use at ordinaryroom temperature, and leaving the ingredients toreact in the saidcontainer.

5. The herein described process of producing satin white, which consistsin mixing a I solution of basic sulphate of alumina,

drate of lime, and a small quantity of water, placing the same beforecomplete reaction in a container at ordinary room temperature, andpermitting final react-ion in the container. 1

6. The herein described method of preparing satin White, which consistsin mingling basic sulphate of alumina, hydrate of lime and enough waterto form a paste only, placing the mixture before complete reaction in ashipping container at ordinary room temperature, and permitting completereaction in the said container.

7. The herein described method of preparalumina and hydrated lime and amuch less quantity of water 7 mg satin white which consists in mixinghighly concentrated basic sulphate of alumina in solution, hydrate oflime, and suflicient water to give a pasty consistency to the mixture,placing the mixture before complete reaction in a shipping container atordinary room temperature, and permitting complete reaction in the saidcontainer.

'- 8. The herein described process of preparing satin White, whichconsists in mixing a concentrated solution of basic sulphate of thansufiicient to thoroughly dissolve the lime and permitting the mixture toreact at ordinary room'temperature, whereby a portion of the lime onlyis brought into solution to acton the sul-' phate of alumina at a time,and on precipitation of the calcium aluminate formed thereby, the watermay become continuously freed to successively dissolve furthe'rquantities of lime to successively react'witlF'the lc ebruary, 1925.

balance of the basic sulphate of alumina until the entire reaction iscomplete.

' 9. The herein described process-of preparing satin white, whichconsists in mixing a concentrated solution of basic's ulphate of aluminaand hydrated lime and a much less quantity of Water than sufficient tothoroughly dissolve the lime and placing the same in a vessel forstorage or shipment and per In testimony whereof, I have signed my nameto 'this specification this 3d day of JOHN F; FREDRIKSSON.

